Change to the description of development is outside the powers of section 73

In doing so, it overturned last year's decision by the High Court.

S73 allows an applicant to apply to vary a planning permission condition, provided that the proposed alteration is not a fundamental change to the development permitted by the original permission. However, it had previously been unclear whether s73 could be used where the new condition directly contradicts the description of development or the 'operative part' of the original permission.

Lord Justice Lewison said that the question was "one of statutory interpretation".

"On receipt of [a s73 application] the planning authority must "consider only the question of conditions", he said. "It must not, therefore, consider the description of the development to which the conditions are attached. The natural inference from that imperative is that the planning authority cannot use section 73 to change the description of the development."

The facts of the case concerned permission granted to install and operate two wind turbines up to a height of 100m. The applicant, Energiekontor UK Ltd sought to vary the permission so that it could build a taller version, showing tip heights of up to 125m.

The s73 application was refused by the local planning authority on the grounds it would have an unacceptable impact on the landscape and would be contrary to policy. A planning inspector allowed Energiekontor's appeal, removing the reference to the tip heights in the description of the permission.

A local resident, John Leslie Finney, applied to the courts to quash the inspector's decision, claiming that the inspector had exceeded her powers under s73. The High Court dismissed his application, ruling that the correct legal test was whether the new conditions were ones which the local planning authority "could lawfully have imposed upon the original permission in the sense that they do not amount to a fundamental alteration of the proposal put forward in the original application".

However, the Court of Appeal overturned the High Court's judgment. Lord Justice Lewison ruled that making changes to the underlying planning permission went against the "purpose" of s73, which is "to give the developer 'relief' against one or more conditions".

"If the inspector had left the description of the permitted development intact, there would in my judgment have been a conflict between what was permitted (a 100 metre turbine) and what the new condition required (a 125 metre turbine). A condition altering the nature of what was permitted would have been unlawful. That, no doubt, was why the inspector changed the description of the permitted development. But in my judgment that change was outside the power conferred by section 73," he said.

Planning law expert Nicholle Kingsley of Pinsent Masons, the law firm behind Out-Law, said: "This case confirms the perennial problem with overly prescriptive descriptions of developments, where for example unit numbers, height or areas are included in the description but should be included in conditions instead - otherwise, it becomes impossible to adjust for inevitable changes as the development progresses without starting from scratch on another permission".

"It was interesting, however, that Lord Justice Lewison mentioned s96A as an available route for minor amendments, and it may lead to such applications being used on existing permissions to put elements of the detailed description into a condition, which can then be changed through a legitimate use of s73. As s96A applications are only available for minor non-material amendments with no right of appeal, I think it is more likely that this judgment will, in practice, lead to an increase in local authorities requiring new planning applications over s73 applications where the amendments conflict with the description of development and particularly as a higher fee is paid for a new application than for a s73," she said.